The present invention relates to implantable medical electrical leads, and more particularly relates to implantable cardioversion/defibrillation leads.
Transvenous cardioversion and defibrillation leads typically employ cardioversion or defibrillation electrodes taking the form of elongated metal coils. These coils may be applied to the exterior surface of the lead body, as disclosed in U.S. Pat. No. 4,934,049 issued to Kiekhafer et al. and optionally thereafter backfilled. Alternatively, the electrode coils may be molded into the electrode body to provide a flush surface or the coils may be machined to provide a flush surface as in U.S. Pat. No. 4,161,952, issued to Kinney et al. The latter approaches provide leads with a uniform outer diameter at the cost of a more complex manufacturing technique. Leads employing coils which are mounted around a lead body having a circular cross-section are substantially easier to manufacture, however, they do provide an increase in lead diameter over the region in which the electrode is located. This in turn requires an increase in the required inner diameter of the introducer used with the lead.